5 Applying what you have read

Mr Ransat was teaching sex determination to Class X.

This term, I have been doing the chapter on heredity and evolution and had just started teaching sex determination. It is a difficult topic for them all to understand well and I don’t really like teaching it. I wanted to try something different so last week for their homework I gave them a problem to think about. They were quite surprised when I said that all they were to do was to think about Sandhya’s situation as normally they have to do lots of writing for me.

I explained that in some communities in India women are under pressure to produce baby boys rather than baby girls. Sandhya had had two girls and was hoping to get pregnant again. Her family sent her into the mountains to see the Baba. He gave her some special medicine and told her that the medicine would make sure that if she had another baby, it would be a boy. The medicine tasted revolting. She was told that it was a mixture of special volcanic ash and water with various herbs and spices.

In the next lesson I asked my students to read the page in the textbook on sex determination. I then told them: ‘Use what you know about “sex determination” from reading the textbook to write a letter to Sandhya’s family to explain how the sex of her baby will be determined and why the medicine will have no effect.’ I gave them five minutes to think about their response on their own and then allowed them to start writing. When they had finished I asked them swap letters with their partner. I asked them to read each other’s and write one comment on it. There was lots of discussion and they became quite animated.

Afterwards, I asked them to think about how communities could be helped to understand the science behind sex determination rather than relying on superstition.

Mrs Nenda has come to end of teaching her Class X students about heredity. She decides to try out the active reading strategy that tests the student’s application of ideas, in this case through the use of a sequence of prepared questions. She differentiates work for students with different attainment levels.

I wanted to check that my students understood fully about basic heredity so I decided to use Strategy 5 from the unit. I particularly liked the idea about getting students to apply their ideas after they have read a section of text.

I looked in the textbook under the section on heredity and found a piece of text about fruit flies’ eyes that explained the basic principles of genetics. It was not very good in terms of its explanations. I knew from experience that my students would not understand it very well. But to save me time to prepare, I thought that I would use it rather than compose my own piece of text. Unfortunately, the questions at the back of the chapter were not very helpful either. I made my own up to go with this section of the textbook. These were:

1. What is R?
2. What is r?
3. What colour eyes will fruit flies with RR or Rr have?
4. What colour eyes will fruit flies with rr have?
5. Draw a punnet diagram to show the possible offspring for two fruit flies who have the genotype Rr.
6. What is the probability that the offspring of these two fruit flies will have red eyes?
7. If there are 20 baby flies, how many are likely to have white eyes?

After looking at the questions again, I realised that a small group of low-attaining students might struggle with them. I made up a second set that I thought would still test the same science but that would be more accessible for these students.

1. R is the allele for … eyes.
2. r is the allele for … eyes.
3. Fruit flies with RR or Rr will have … eyes.
4. Fruit flies with the alleles rr will have … eyes.
5. Complete the punnet diagram to show the possible offspring for two fruit flies who have the genotype Rr.

6. The probability that the offspring of these two fruit flies will have red eye is …
7. … of the 20 baby flies are likely to have white eyes.

I used both sets of questions in class after my students had read the section in the textbook. We marked the answers together so that I could get some instant feedback. I was really pleased with the outcomes. My low-attaining students did just as well on the questions as the rest of the class. I think rephrasing the questions for the lower attaining students was a good strategy. The downside was that I had to spend more time planning, but this saved me time in the lesson as the students did not ask for help. They happily got on with their questions.

The main positive outcome from the lesson was the improvement in the confidence of this group of students. The instant feedback seemed to help all of my students know how well they had done. The lower attaining students realised that they could do the science just as well as everybody else. I knew that all my students had obtained a better understanding of the basic principles of genetics, than if they had just read the textbook. I will use this idea again.